END-POINT MEASURES IN RHEUMATOID-ARTHRITIS CLINICAL-TRIALS - GROUP SUMMARY AND INDIVIDUAL PATIENT ANALYSIS

Objective. To evaluate the responsiveness of measures of disability, d iscomfort, and disease process in rheumatoid arthritis (RA) clinical t rials, when used as group summary variables and as variables of indivi dual patient improvement. Methods. Disease outcome and process measure s were assessed in 97 patients with RA of recent onset, who were parti cipating in a prospective trial comparing the effectiveness of several drug treatment strategies. Measurements were done after 3 and 6 month s of treatment. Group summary analysis was performed with tests of sta tistical significance of changes, and by calculating effect sizes (i.e ., mean change in an endpoint divided by its standard deviation). Indi vidual patient improvement was defined as improvement of greater than or equal to 33% compared to baseline, according to recommendations of the recently held Conference on Outcome Measures in Rheumatoid Arthrit is Clinical Trials. Results. Almost all mean group changes in endpoint s were statistically significant (p < 0.001). Effect sizes and figures on individual patient improvement provided additional information: ph ysical discomfort measures were rapidly responding measures that did n ot further improve after 3 months; disease process measures, joint cou nt, erythrocyte sedimentation rate and C-reactive protein also respond ed quickly and kept improving up to 6 months; the disability measures were relatively unchanged at 3 months, and only the self-report questi onnaire score showed considerable improvement at 6 months. Conclusion. Effect sizes and data on patients who showed clinical improvement in disease process or outcome measures offset the strongly significant p values of statistical tests for almost all endpoint measures. Although discomfort measures rapidly responded to therapy, disability and dise ase process measures may not reach optimal improvement within 6 months .